Photolog in Japan with my poor English ability

Blue spots in the pictures

These photos were taken in Itako, Japan, the last Saturday.
Iris festival have been held.
The Iris flowers were floodlit in the night.
Can you see blue spots extra in the following photos.
What are they ?
They are Inori Boshi setted on the river near the Iris Garden.
Please, see also this post about the old custom with wooden boats in this town.